Rebkong Amdo Tibetan is that variety of Amdo Tibetan (ISO 639-3 code adx) spoken in Tongren County, Huangnan Tibetan Autonomous Prefecture, Qinghai Province, in north-west China. With this study I hope to contribute as explicitly phonological a discussion of Rebkong Amdo Tibetan as Sun (1986) did for Ndzorge, Janhunen & Norbu (1999) did for rDo-sbis, Makley et al. (1999) did for Labrang, Haller (2004) did for Themchen, and Peet did in his 2007) study, along with all the data necessary to justify my analysis. This growing collection of phonological analyses of Amdo Tibetan dialects contributes to an understanding of the phonological characteristics of the Amdo dialect group in general, and facilitates the investigation of variation from one variety to another. In addition, the identification of shared features among Amdo Tibetan phonological systems has implications for the study of Tibetan historical phonology in general. Most analyses of Amdo Tibetan dialects report a marginal three-way contrast between voiced, voiceless unaspirated, and voiceless aspirated stops and affricates at each place of articulation. The present analysis posits only two contrastive series for Rebkong Amdo Tibetan, in agreement with Janhunen & Norbu’s (1999) analysis of rDo-sbis Amdo Tibetan. Rather than conclude that Rebkong and rDo-sbis are somehow unusual in this respect, it is instead suggested that this analysis can be equally applied to many, perhaps all, other varieties of Amdo Tibetan. Comparison with discussions of Classical Tibetan and Proto-Tibeto-Burman further suggest that Amdo Tibetan may have always only had this two-way contrast.